Means for preventing moisture condensation upon refrigerator windows



Oct. 7; 1941. I J. P. GREEN, 2,257,948

MEANS FOR PREVENTING MOISTURE CONDENSATION UPON REFRIGERATOR WINDOWSFiled Feb. 7, 1940 Patented Qct. 7,1941

8 FOR r0 MOISTUB MEAN ' CONDENSATION UPON REFRIGERATOR WINDOWS John P.Green, was... Pa. Application February I, 1940, Serial No. 317,832 18Claims. (Cl- B289.5)

This invention relates to new and useful improvements in refrigeratorconstruction whereby frosting or condensation of moisture on the windowglass or other surfaces thereof is prevented and the pressure betweenthe several panes of a multi-paned window is brought and maintainedclosely to atmospheric thus eliminating the danger of moistureinfiltration because of external leaks.

More particularly the invention relates to the 1 prevention of frostingand condensation on multipaned windows of low temperature refrigeratorssuch as those used for the-storage and display of frosted or frozenfoodstuffs and the like.

The invention also involves the provision of an arrangement wherebydisplay refrigerators can be glazed without the use of special rooms inwhich atmospheric conditions are maintained in. order to prevent theinclusion of air of high moisture content between the of the window, andenables, further, the elimination of the necessity for using chemicalmoisture absorbing compounds in order to remove any moisture occludedbetween said panes or exuded by the framing material or the materialsused in glazing the refrigerators.

' such a construction objectionable moisture has been found to bedepositedon the panes due to the fact that their outer surfacetemperatures are at times below the dew points of the air in contacttherewith. I

In addition to the formation of frost or conatmosphere surrounding therefrigerator upon the exterior surface of the outer pane of themuiti-paned window in said refrigerator.

with these and other objects in view, the invention consists in thevarious features of construction, combination and arrangement of partshereinafter fully set forth and shown inithe accompanying drawing, inwhich:

Figure l. is aview in perspective of one form of refrigerator of thedisplay type embodying the present invention;

Figure 2 is an enlarged fragmentary sectional perspective view of thewindow construction of the refrigerator shown in Figure 1; and

Figure 3 is a fragmentary view in perspective showing a modification ofone feature of the obliquely disposed display window 2 in thefront ofthe refrigerated chamber thereof.

As shown in Figure 2 of the drawing the window 2 is comprised of fourspaced panes of glass 3, l, 5 and 8 mounted within a frame I and spacedfrom each other by'suitable sealing strips 8 and 9 respectively, to forminsulating air spaces ii, I! and it between said panes I, l, 5 and B,the outer pane 6 being sealed against the infiltration of air. from theexterior of the case by a suitable sealing compound it held in place bystrips Illa.

As the air within the refrigerator has been cooled to a temperature'below that existing between the several panes of the window, such airwill, if permitted to circulate in proper amount through the aforesaidair spaces ii, i2 and I3, not only fail to precipitate moisture but willabsorb any moisture within these spaces with the densation upon thepanes, another difficulty is 40 result that condensation upon thesurfaces of present due to the condensation of moisture upon theexterior surface of the outer pane when, under certain climaticconditions, the dew point ofthe air in contact with the outer surface ofthis outer pane is exterior surface of this outer pane. This occurs intimes of high relative humidity of the atmosphere in the room or placewhere the refrigerator is located.

with the foregoing observations in mind, the object of the presentinvention is to provide a multi-paned windowfor a lowtemperaturerefrigerator so constructed and arranged as to maintain vair havingsuiliciently low relative humidity in contact with the surface orsurfaces of said panes that moisture or frost will not be deposited onthe surfaces of said panes.

A further, but equally important object of this invention is to providea novel means for preventing the condensation of moisture said panes isentirely eliminated and unobstructed" clear vision therethrough to theinterior of the case is insured at all times.

In order effectively to accomplish this, the botabove the temperature ofthe 45 tom frame member la is provided with a series of spaced groovesor slots i4, i5 and i8, and these are so located and spaced with respectto each other and the panes of glass 3, 4, 5 and 6 that they arerespectively disposed centrally below or at the bottoms of the insulatedair spaces il. l! and I3 between the said panes. Similarly the top framemember 11) is provided with like grooves or slots II, II and I! whichreside respectively at the tops of said insulated air spaces H, II andI3.

To provide for communication between the several grooves or slots I4, I!and it and the respective insulated air spaces i i, i2 and .II, thebottom insulating and spacing strips I are each from th provided withsuitable openings to, 8b and 9c therethrough which respectively registerwith the said grooves or slots l4, l3 and ll, Likewise the topinsulating and spacing strips 3 are pro vided respectively with openings3a, 3b and 30 which respectively register with the grooves or slots l1,l3 and I! in the top frame member 1b.

In order to permit air from the interior of the case to enter the spacel2 between panes 4 and 3, I provide an opening 20 to the central grooveor slot II in the bottom frame member or portion la, and also provide asecond opening or slot 2i which communicates inwardly with said duct 23i thus providing dual air openings to the said groove or slot II andinsuring continued circulation should one or the other of them becomeobstructed due to foreign objects coming in contact therewith.

In order to prevent any infiltration of dust or other foreign matter tothe insulating air spaces ii, l2 and i3, the aforementioned centralgroove or slot It, or the opening 20, is packed with a loose porousmaterial 22 saturated or coated with a non-drying liquid substance suchas calcium chloride or the like or with a substance or material havingsuitable adhesive properties such as, for example, Vaseline.

Between the grooves or slots l1 and i3 and providing communicationbetween spaces II and- I2 is a duct or ducts 23 formed in the upperframe member lb. Likewise between grooves or slots l4 and i6 andproviding communication between the spaces II and I3 is a duct or ducts24 formed in the bottom frame member Ia. In addition, and to provide anoutlet to the interior oi the case from the space 13 a duct or ducts 2!is formed in the upper frame member lb so as to communicate between theslot l3 andan outlet slot 20 formed or provided along the upper interiorsurface of the innermost pane of glass 3.

In order to obtain optimum results from the invention too great emphasiscannot be laid upon the location of the outlet opening 26 of the returnduct 25 to the interior of the refrigerating chamber in order to preventstoppage of said opening due to the collection and freezing chamber at apoint or points immediately ad-' jacent the top interior surface of theinnermost pane 3 as indicated at 26, the air preferably actually passingin' contact with the surface of said pane 3.

If necessary, in order further to protect the outlet of the returnpassageway or duct 25 from the low temperature of the refrigeratingchamber and insure maintenance of the surface of this pane 3 above thedew point of the returning air, a shield 21 may be disposed .along theinterior of the top frame portion so as to depend therebelow and overliethe outlet of said return duct 25, said shield, however, should notdepend a distance which will reduce materially the field of visionthrough the window 2.

outlet adjacent the upper interior surface of the pane 3 as aforesaid,it is pointed out that the said air may be returned as indicated at 20a(dotted lines) to any point or zone within the refrigerator wherein thetemperature is above the dewpoint of said air, and with equallysatisfactory results, as for example, by extending the return air outletinto the interior of the cabinet and artificially heating the outlet, asindicated at 23, either electrically orby the hot compressor gases or byextending the said return air outlet into the warmer temperature zonejust above the expansion unit which is present in all artificiallycooled refrigerators.

Now, in illustration 'of the invention, as the air within space l2,under operating conditions, will be at a higher temperature than the airwithin the cabinet, there will exist a slight pressure differencebetween opening 3b and the inlet openings 20 and 2| with the result thatair from within the cabinet is drawn into the insulating space i2causing the air therein to be displaced slowly upward and outwardlytherefrom through the opening 8b. As the air thus entering the space i2is raised in temperature, its relative humidity is lowered and anymoisture within the said space l2 will be absorbed'and will not bedeposited on the surfaces of the panes of glass 4 and I.

. Similarly, as the air ,within the space H is at a lower temperaturethan the air within space l2 there exists a sufficient pressuredifferential between openings 3b and 3a to cause air within the space i2to be forced into said space i I and displace the air in that spacedownwardly and out of the opening 30. As this air which is forced intothe space Ii is at a temperature sumciently higher than when in therefrigerated case the said air will be above the dew point and nomoisture will be deposited on the surfaces of:the panes 3 and l ofthe'window.

Finallyyas the air within space I3 is at a higher temperature than theair in space H, a pressure difference will exist between the openings 3aand 30 with the result that air from space II is caused to flow throughpassage 24 and upwardly through slot i6 into space l3 forcing the airtherein to be displaced upwardly outwardly through opening 30, groove i9and passage 25 from which it is returned to the interior of the cabinetthrough the outlet opening 23.

Now as respects the prevention of moisture condensation on the exteriorsurface of the outer pane 6 under certain climatic conditions, I havefound that if, during periods of such conditions, said exteriorsurfaceof the outer pane 3 is heated to or maintained at a temperature equal toor above the dew point of the atmosphere in which the refrigerator islocated, this condensation of f moisture can be successfully eliminated.

While, for purposes of economy in construc- Therefore, according to thepresent invention, I dispose a heating element or means 23 along theexterior of the outer pane 8 and in contact with the exterior surfacethereof, preferably near an edge as shown in Figure 2 of the drawing.This heating element or means 23 may, for example, be either aresistance element through which a suitable electric current is passedor may be a pipe or conduit through which the hot refrigerant from thecompressor passes. As hereinbefore stated this condensation conditiondoes not continuously occur and therefore the heating element or means28 need be operated onlywhen it is necessary to keep the temperature ofthe exterior surface of the outer pane 8 above the dew point of thesurrounding; atmosphere. Of course. while the heating element It isshown as located adjacent and along the lower or bottom exterior edge ofthe outer pane of glass 6, it will be obvious that such position is notessential and that such heating element may be placed adjacent to andalongi any one or more edge or other exterior surface portions of saidouter pane 6 with satisfactory results.

From the foregoing it will be observed that the present inventionprovides a refrigerator window construction and arrangement wherebymoisture condensation on the several panes of said window may besuccessfully and entirely eliminated,

and that said construction and arrangement by which such results areobtained is relatively simple and inexpensive although it iscomparatively rugged.

Although the descriptiongand illustration of the invention havebeen-shown as applied to a four-paned window, it will be obvious, ofcourse,

that only three or even a greater number of panes may be employed vby arepetition of the circulation in the case of aneven number of a ing air.

refrigerating chamber in a zone therein having a temperature above thedew point of said return- 4. In a refrigerator having a display windowin the refrigerating chamber thereof comprising a plurality of panes oftransparent material 5. In a refrigerator having a display window in'the refrigerating chamber thereof comprising a plurality of panes oftransparent material spaced from each other to provide a plurality ofinsulating air spaces therebetween, air passageways panes, or byconnecting any two adjacent air spaces so that for all practicalpurposes there exists an odd number of circulating spaces in the casewhere an odd number of panes is employed.

Also, while a particular structural embodiment of the features 'anddetails of the invention has been illustrated and described it is notintended that the invention be limited thereto but that changes andmodifications may be incorporated and embodied therein as desired withinthe scope of the annexed claims.

I claim:

' 1. In a refrigerator havinga display window in the refrigeratingchamber thereof comprising a plurality" of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to thinsulating air spaces, and a return air passageway from said insulatingair spaces opening to the refrigerating chamber at a .point adjacent theupper edge portion of the interior surface of the inner pane oftransparent material. I

2. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to the in--sulating air spaces, and a return air passageway from said insulatingair spaces opening to the refrigerating chamber at a point adjacent theupper edge portion of the interior surface of the inner-pane oftransparent material, and means for heating the exterior surface of theouter paneof transparent material disposed along an exterior surfaceportion thereof.

3. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air pas-. sage from said refrigerator chamber to one ofthe insulating air spaces, other air passages communioating between saidinsulating air spaces and arranged so that air from the chamber willflow through the spaces in predetermined sequence, and a return airpassageway from the air space last in said sequence opening to theproviding communication serially between said insulating air spaces, anair passage ffom said refrigerator chamber to an outer one of theinsulating air spaces, a return air passageway opening toltherefrigerating chamber at a point adjacent the upper edge portion of theinterior surface of the inner pane of transparent material, and meansfor heating the exterior of the outer pane of transparent materialdisposed along an exterior surface portion thereof.

6. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, air passageways providing communication serially betweensaid insulating air spaces, an air'passage from said refrigeratorchamber to an outer one of the insulating air spaces, and a return airpassageway opening to the refrigerating chamber in a zone therein havinga temperature above the dew point of the returning air.

'7. In a refrigerator having a display window in the refrigeratorchamber thereof comprising four panes of transparent material spacedfrom each other to provide inner, intermediate and outer insulating airspaces between respectively adjacent panes; an air passageway providingcommunication from said refrigerator chamber to said intermediateinsulating air space, other air passageways providing communication fromthe intermediate to said inner and from the innerto'said outer airspaces respectively, and

a return air passageway from the outer air space to the refrigeratorchamber opening to the latter at a point adjacent the upper edge portionof the interior surface of the inner pane of transparent material.

8. In a refrigerator having a display window in the refrigerator chamberthereof comprising four panes of transparent material spaced from eachother to provide inner, intermediate and outer insulating air spacesbetween respectively adjacent panes, an air passageway providingcommunication from said refrigerator chamber to said intermediateinsulating air space, other air passageways providing communication fromthe intermediate to said inner and from the inner to said outer airspaces respectively, return air passageway from the outer air space tothe refrigerator chamber open ng to the latter at a point adjacent theupper edge portion of the interior surface of the inner pane oftransparent material, and means for heating the exterior surface of the.outer pane of transparent material disposed along an exterior surfaceportion thereof.

9. In a refrigerator having a display window in the refrigerator chamberthereof comprising four panes of transparent material spaced from eachother to provide inner, intermediate and outer insulating air spacesbetween respectively adjacent panes, an air passageway providingcommunication from said refrigerator chamber to said intermediateinsulating air space, other air passageways providing communication fromthe intermediate to said inner and from the inner to said outer airspaces respectively, and a return air passageway from the outer airspace to the refrigerator chamber opening to the latter in a zonetherein having-a temperature above the dew point of the returning air.

10. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to theinsulating air spaces, and a return air passageway from said insulatingair' spaces opening to the refrigerating chamber at a point adjacent theupper edge portion of the interior surface of the inner pane oftransparent material, and a protective shield disposed within saidchamber and overlying the opening of said return air passageway.

11. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to theinsulating air spaces, a return air passageway from said insulating airspaces opening to the refrigerating chamber at a point adjacent theupper edge portion of the interior surface of the inner pane oftransparent material, a protective shield disposed within said chamberand overlying the opening of said return air passageway, and'means forheating the exterior surface of the outer pane of transparent materialdisposed along an exterior surface portion thereofl 12. In' arefrigerator having a display window 'in the refrigerator chamberthereof comprising four panes of transparent material spaced from eachother to provide inner, intermediate and outer insulating air spacesbetween respectively adjacent panes, an air passageway providingcommunication from said refrigerator chamber to said intermediateinsulating air space, other air passageways providing communication fromthe intermediate to said inner and from the inner to said outer airspaces respectively, a return air passageway from the outer air space tothe refrigerator chamber opening to the latter at a point adjacent theupper edge portion of the interior surface of the inner pane oftransparent material, and a-protective shield disposed within saidchamber and overlying the opening of said return air passageway.

13. In a refrigerator having a display window in the refrigeratorchamber thereof comprising four panes of transparent material spacedfrom each other to provide inner, intermediate and outer insulating airspaces between respectively adjacent panes, an air passageway providingcommunication from said refrigerator chamber to said intermediateinsulating air space, other .air passageways providing communicationfrom the ntermediate to said inner and from the inner to said outer airspaces respectively, a return air eway from the outer air space to therefrigerator chamber opening to the latter at a point adjacent the upperedge portion of the interior surface of the inner pane of transparentmaterial, a protective shield disposed within said chamber and overlyingthe opening of said return air. eway, and means for heating the exteriorsurface of the outer pane of transparent material disposed along anexterior surface'portion thereof.

14. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to theinsulating air spaces, a porous filter in said.air passage, and a returnair passageway from, said insulating air spaces opening to therefrigerating chamber at a point adjacent the upper edge portion of theinterior surface of the inner pane of transparent material.

15. In a refrigeratorv having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality to the refrigeratingchamber at a point adjacent the upper edge portion of the interiorsurface of the inner pane of transparent material.

16. In a refrigerator having a display window in the refrigeratingchamber thereof comprising a plurality of panes of transparent materialspaced from each other to provide a plurality of insulating air spacestherebetween, an air passage from said refrigerator chamber to theinsulating air spaces, a filter in said air passage composed of porousmaterial coated with an adhesive substance, and a return air passagewayfrom said insulating air spaces opening to the refrigerating chamber ata point adjacent the upper edge portion of the interior surface of theinner pane of transparent material.

17. In a refrigerator case maintaining subfreezing temperatures thereinand having a window consisting of a plurality of spacedpanes of the airthereto at a point therein maintained at a temperature above the dewpoint of the said air.

18. In a refrigerator case maintaining subfreezing temperatures thereinand having a window consisting of a plurality of spaced panes oftransparent material, the method of preventing frosting and condensationon the several panes I of said window comprising circulating air fromthe refrigerator case through the several spaces between said panes,returning said air to said refrigerator case, and protecting the returnair outlet so as to maintain the temperature thereof above the dew pointof the air.

JOHN P. GREEN.

